Voltage regulator for electric generators



Jan. 26, 1943 w. G. I WEATHERLY 2,309,558

VOLTAGE REGULATOR FOR ELECTRIC GENERATORS Filed Sept. '16, 1941 WILLJAM6. WEATHERLY 8 @NM W! Patented Jan. 26, 1943 OFFICE VOLTAGE REGULATORFOR ELECTRIC GENERATORS William G. Weatherly, Wenatchee, Wash.

Application September 16, 1941, Serial No. 410,990

1 Claim.

This invention relates to controls for automobile generators of the typeoperating to adjust the generator output to the load requirements.

The principal object of this invention is to provide a means to assure anearly constant voltage.

A second object of this invention is the provision of such means in a.compact and inexpen sive form readily adaptable for installation as apart of automobile electrical systems.

Other objects and advantages will be apparent in the followingdiscourse,

In the drawing:

The figure is a diagrammatic representation of the elements embodied incombination.

The essence of this invention resides in the means provided to effectthe regulating operation in degrees unrelated to the value of potentialincrease upon which the device relies for control.

Referring now more particularly to the draw- A generator I is wound witha shunt field 2 and a control field 3 the force of which opposes theshunt field. A storage battery 4 of conventional type is connected inparallel to the generator I. Interposed in the shun-t field circuit is aresistance 5, an actuating coil 6, and the control field in seriesconnection. A pilot coil I connected across the generator output asindicated, and a compensating coil 8 connected in series with the load,together with the actuating coil 6, are windings controlling thelongitudinal movement of a core 9 in conventional solenoid arrangement Aframe I0 is rigidly attached to the core 9 at one end and carries at itsextremity the sliding contact H, slidable along the resistance 5. Thisslidable contact I I is connected to the ground as indicated. A tensionspring l2, secured at opposite ends to a stationary attachment I3 and ahook ll formed upon the frame 10, urges the core 9 to a normal positionwithin the coils 6, 1, and 8.

Heretofore, it has been common practice in devices of this type to use apotential coil, analogous to the pilot coil 1 in the presentapplication. to actuate a variable resistance in certain degreesproportional to the voltage increase. In such types of control devices,it will be recognized that as the load requirements diminish the voltagewill constantly rise owing to the necessity of the use of increasingforces to actuate the variable resistance to its fullest capacity.

In contrast to this practice. the present invention contemplates themaintenance of a predetermined nearly constant voltage. This isaccomplished by providing the energy for the operation of the variableresistance from a separate source, but, in turn controlled by thebehavior of the pilot coil 1 which registers a voltage rise of almostany practical value. The magnetic force developed by a minimum voltagerise, though insufficient to actuate the core and hence the variableresistance through amplitudes ef fective to prevent voltage rise,operates to energize the actuating coil 6 by diverting additionalcurrent therethrough.

To trace the operation of the device in detail:

The pilot coil 1, being connected across the generator output, willrespond to the slightest voltage rise to exert a force on the core 9 of,let it be assumed, a minimum value. As soon as the shunt field circuitis completed to ground through one end of the resistance 5 and thesliding contact II, and the control field circuit is likewise completedto ground through the remaining end of the resistance 5 and slidingcontact H, the slightest movement of the contact I i, in response to theaction of the pilot coil 1, will result in an adjustment of theproportions of the generator current which fiow through the shunt fieldand control-field windings respectively.

This alteration of the intensity of the current fiowing in the circuitswill thus alter the value of the current in the actuating coil 6 in amanner to augment the effects produced upon the core 9 by the pilotcoil 1. Thus, in a sense, the device may be said to be regenerativelyactuated. That is to say, the action of the pilot coil 1 may beamplified in any desired degree by a choice of the ampere-turncapacities of the coils 6 and I, coupled with the selection of asuitable potential gradient characteristic for the resistance 5.

Let it be assumed that an increase in voltage of one fourth of a volt isnecessary to actuate the core 9 through a movement effective to registera change in the relative resistance values of that part of theresistance 5 considered, and that a variation of one fourth of a volt iswithin the tolerance for which the apparatus as a whole is designed. Itwill be apparent that regardless of the magnitude of the load, anincrease in generated voltage of one-fourth volt will result in thecurtailment of'the generator output to the precise requirements of theload.

The compensator coil 8, exerting force in opposition to those of thecoils 6 and 1, modifies the precise position of the sliding point II atwhich the regulation occurs. As the compensator coil 8 is in series withthe load, it will be apparcut that as the load increases, resistancewill be cut out 01 the shunt winding and cut into the control-field,thus providing for the increased field strength necessary to carry theincreased load.

Proper determination of the current-carrying capacities of the severalcoils and resistances employed will insure maximum eiiiciency andminimum of heat losses.

While I have shown a particular form of embodiment of my invention, I amaware that many minor changes therein will readily suggest themselves toothers skilled in the art without departing from the spirit and scope ofthe invention. Having thus described my invention, what I claim as newand desire to protect by Letters Patent is:

Generator control apparatus comprising in combination with a generatorhaving a shunt held and a control winding magnetically associated tooppose the field, a resistance and an actuator coil connected togetherin series and to one terminal each of said field and said controlwinding respectively, a pilot coil connected across the generator outputmagnetically associated with said actuator coil, a compensating coilconnected in series with a load and the generator output magneticallyassociated with said actuator and pilot coils, the latter coils beingwound to magnetically oppose said compensator coil, a core operablethrough said actuator, pilot, and compensator coils, means urging saidcore in op position to the magnetic etlects thereupon of said actuatorand pilot coils, and selective tap means associated with said resistancecontrolled by said core to complete the circuit with the generatoroutput of the said field through a portion 01. said resistancedetermined by the relative adjustment of said tap the remainder of whichis in series through said tap with said control winding across thegenerator output.

WILLIAM G. WEATHERLY.

